Pai-based coating compositions

ABSTRACT

A process for PAI-based coating compositions. An embodiment of a method includes manufacturing a coating composition, the manufacturing of the coating composition including mixing a first solvent, the first being solvent being N-formyl morpholine (NFM), with a second solvent to form a first solution; dissolving polyamideimide or polyamide amic acid resin polymer (PAI) in the first solution; precipitating a PAI compound from a mixture of MEK and the first solution; and dissolving the PAI compound in a second solution to generate a coating solution.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present patent application claims priority to and incorporates byreference U.S. Provisional Patent Application No. 62/346,440, entitled“Novel Full Scale Process for Preparing Polymer Powders”, filed on Jun.6, 2016; U.S. Provisional Patent Application No. 62/346,443, entitled“Preparation Of Polyamide-Imide Resins Using N-FormylMorpholine:3-Methoxy N,N-Dimethylpropanamide”, filed on Jun. 6, 2016;and U.S. Provisional Patent Application No. 62/347,020, entitled“PAI-Based Coating Compositions”, filed on Jun. 7, 2016.

TECHNICAL FIELD

Embodiments described herein generally relate to the field of chemicalprocessing, and, more particularly, to PAI-based coating compositions.

BACKGROUND

Polyamideimide and polyamide amic acid resin polymers (hereinafterreferred to as PAI) are well-known thermally stable polymers that areused for many high performance coating applications due to theirexcellent adhesion, temperature resistance, and high strength.

The primary route to synthesizing polyamideimide polymers in a form thatis convenient for the manufacture of coatings is by reactingdiisocyanate, often 4,4′-methylene diphenyldiisocyanate (MDI) withtrimellitic anhydride (TMA). In this process, PAI polymers are typicallymanufactured in polar aprotic solvents such as N-methyl amide compoundsincluding dimethylformamide, dimethylacetamide, N-methylpyrrolidone(NMP), N-ethylpyrrolidone.

However, with increasing regulation of certain materials and compounds,the solvents used in these polymerizations of the coating compound haverecently come under scrutiny due to toxicological concerns. Thus, thereis a need for generation of coating compounds that provide performancecharacteristics that are comparable to existing coating applications,while utilizing a safer solvent composition.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments described here are illustrated by way of example, and not byway of limitation, in the figures of the accompanying drawings in whichlike reference numerals refer to similar elements.

FIG. 1 is a flow chart to illustrate generation of a coating compositionaccording to an embodiment;

FIG. 2A is a table to summarize a first part of the informationregarding the examples according to the respective embodiments;

FIG. 2B is a table to summarize a second part of the informationregarding the examples according to the respective embodiments;

FIG. 2C is a table to summarize a third part of the informationregarding the examples according to the respective embodiments; and

FIG. 2D is a table to summarize a fourth part of the informationregarding the examples according to the respective embodiments.

DETAILED DESCRIPTION

Embodiments described herein are generally directed to PAI-based coatingcompositions.

For the purposes of this description:

“PAI” refers to polyamideimide and polyamide amic acid resin polymers.

In some embodiments, a process is described for generation of aPAI-based CMR-free (CMR: carcinogenic, mutagenic, reprotoxic) coatingcomposition that provides comparable performance characteristics toexisting coating compositions.

A relatively clear, CMR-free (CMR: carcinogenic, mutagenic, reprotoxic)PAI coating composition solution may be derived from a PAI powder,including, but not limited to, any of processes described in Examples IIand XI of U.S. provisional patent application No. 62/346,440, entitled“Novel Full Scale Process for Preparing Polymer Powders”, filed on Jun.6, 2016, and U.S. patent application Ser. No. ______, entitled “FullScale Process for Preparing Polymer Powders”, where there are effectiveratios of reaction solvent, co-solvents and polymer (e.g., polyamideimide) to one another. Properties of the coating solution, such assolubility in polar aprotic solvents, may depend at least in part uponproperties of the PAI powder chosen. PAI coating solutions based onpowders are not limited to being composed of organic solvents, but mayalso be used to make water-based formulations by utilizing amines suchas DMEA (dimethylethanolamine).

The rate at which the PAI powders dissolve as well as the stability ofthe resulting water-based coating solution are some examples ofparameters to be considered for determining whether a particularcombination, and particular ratios, of solvent, co-solvent and polymerare to be effective for the manufacture of a PAI-based coatingcomposition. In some embodiments, films on aluminum substrates and novelfree-standing films may be produced from CMR-free and comparative PAIcoating solutions. In some embodiments, films cast from CMR-free coatingsolutions derived from PAI powders provide similar physical andmechanical properties to those made from NMP and NEP-based materialswhile utilizing a safer solvent composition.

Polyamide-imides are high performance polymers with exceptional thermal,mechanical, and chemical resistant properties. As either thermosettingor thermoplastic amorphous polymers, polyamide-imides are used in highperformance coating applications. The strength, flexibility, meltprocessability, and adhesive properties compound polyamide-imide'scoating benefits. These benefits are derived from a beneficial synergybetween the polyamide and polyimide. Regulation of the solvents used inthe synthesis and formulation of the polymer has driven research toreduce the use of known hazardous materials.

One advantage of the technology relates to the production ofpolyamide-imides without the use of carcinogenic, mutagenic, orreprotoxic (CMR) materials. The sunsetting of MDA (carcinogenic) andreclassification of NMP (a traditional solvent for PAI polymerization)as reprotoxic dictates the need for alternative means of PAI production.The technology described in U.S. provisional patent application No.62/346,440 and U.S. patent application Ser. No. ______ uses MDI(4,4′-methylene diphenyldiisocyanate) and CMR-free solvent systems. Insome embodiments, a process generates an improved CMR-free highlycross-linked PAI coating on a substrate derived from a PAI powder, thusproviding a coating with desirable performance characteristics in asafer solvent composition. Herein, the term “polyamideimide” (or “PAI”)also includes polyamic acid and salts of polyamic acid from whichpolyamideimide may be derived.

There are numerous parameters that play a role in whether or not a PAIcoating solution will be effective and have the desired thermal,mechanical, and electrical properties. The first of such parameters issolvent selection. Solvents commonly used in polyamide-imide includeNMP, NEP, and DMAc, though there are restrictions on the use of thesesolvents in Europe due to their toxicological properties. The solventchoice can affect the dissolution time of the PAI powder, thespreadability/wettability of the resulting coating, the temperature atwhich the coating solution cures, the cure rate, and numerous otherimportant properties.

In addition to the selection of a solvent to obtain the desired matchbetween the PAI coating at the surface, there are numerous substrates towhich the generated coating may be applied, including glass or metalpipes, pots, pans, cans, or rubber rollers. In addition, the surfacechemistry and roughness of a substrate can also be altered to affect thecoating. In some embodiments, glass panels are etched with HF(hydrofluoric acid) prior to applying the PAI coating formulation toallow maximum coverage with minimal surface defects such as pin holes orfish eyes. In some embodiments, after curing, the coated glass panelsare placed in a humidity chamber for various amounts of time to aid inthe release of the coatings from the substrate. These surface alteringtechniques aid in the production of defect-free films suitable for dogbone fabrication and tensile testing.

The solvent selection, along with the concentration, also affects theviscosity of the generated coating solution. An appropriate boilingpoint is one consideration. Solvents with boiling points in the range of150-240° C. have proven to be most suitable for coating applications.The desired viscosity of the coating solution can be dependent upon theapplication and whether the coating solution is brushed, rolled, dipped,misted, sprayed, or applied using any other known application by thosewho are skilled in the art. Various viscosity modifiers and thinningsolvents can be added to the coating solution to reduce the viscositywithout adversely affecting the performance which include but are notlimited to methyl ethyl ketone, 1-butanol, 2-propanol, acetone,triethylene glycol, propyl propionate, propylene glycol methyl ether,propylene glycol propyl ether, methyl acetate, ethyl acetate, andmixtures thereof.

In some embodiments, PAI powder is isolated from a NFM:MEK solution byprecipitation into excess MEK, wherein NFM refers to N-formyl morpholineand MEK refers to methyl ethyl ketone. The powder is then subsequentlyused to make a CMR-free coating formulation by re-dissolution intosolvents such as NBP and other co-solvents (as illustrated in ExamplesI-XI below), wherein the viscosity of the resulting solution may then bemeasured. In some embodiments, PAI coatings ranging from 5-100 μm inthickness are created using CMR free solvent systems, with thepercentage of solids ranging from 4-40% solids.

In some embodiments, high acid number (high polyamic acid content) PAIpowder as described in U.S. provisional patent application 62/346,440and U.S. patent application Ser. No. ______ is utilized to make aCMR-free ethylene glycol solvent-based coating solution, as demonstratedin Example XIII of this embodiment. In some embodiments, both types ofpowders are re-dissolved in and reacted with water and amine to giveaqueous coating formulations (Examples XIV and XV, respectively).Aqueous-based coating compositions comprised of this polyamic acid saltform of the polymer have been used in a variety of applications rangingfrom cookware to coating and sizing fibers, metal surfaces, glasssubstrates, and other materials. Parameters such as the dissolution timeof the powders and stability of the coating solutions were explored.Free-standing films of CMR-free and NMP/NEP-based PAI coating solutionswere made along with films on Al substrates. The mechanical propertiesof the films were measured and found to be comparable.

FIG. 1 is a flow chart to illustrate generation of a coating compositionaccording to an embodiment. In some embodiments, a method includesmanufacturing a coating composition 100, the manufacturing of thecoating composition including:

Mixing a first solvent, the first solvent being N-formyl morpholine(NFM), with a second solvent to form a first solution 105, wherein thefirst solution includes polyamideimide or polyamide amic acid resinpolymer (PAI). In some embodiments, the second solvent is methyl ethylketone (MEK), as illustrated in FIG. 1.

Precipitating a PAI compound from a mixture of MEK and the firstsolution 115.

Dissolving the PAI compound in a second solution to generate a coatingsolution 120, where the second solution is formed of N-butyl pyrrolidone(NBP), ethylene glycol, or a solution of an a) amine, b) one or moresolvents, and c) water 125.

In some embodiments, the second solvent is a precipitation solventselected from, but not limited to, alcohols, amides, acetates,aldehydes, ethers, ketones, lactams, pyrrolidones, morpholines,morpholine derivatives, sulfoxides and mixtures thereof.

In some embodiments, the second solution is formed with NBP. In someembodiments, the second solution is further formed with one or moreorganic co-solvents. In some embodiments, the one or more co-solventsinclude n-butyl acetate. In some embodiments, the one or moreco-solvents include cyclohexanone. In some embodiments, the one or moreco-solvents include 3-methoxy N,N dimethylpropanamide (MDP). In someembodiments, the one or more co-solvents include 2-octanone.

In some embodiments, the second solution is 100% ethylene glycol. Insome embodiments, the first solution for dissolving of the PAI furtherincludes Triethyl amine (TEA) and water to generate the tertiary aminesalt of the polyamide-amic acid prior to precipitation.

In some embodiments, the second solution comprises a) an amine, b) oneor more solvents, and c) water. In some embodiments, the amine is atertiary aliphatic amine, the amine being dimethylethanolamine (DMEA),and the one or more co-solvents are N-methylpyrrolidone (NMP) and1-methoxy-2-propanol (propylene glycol methyl ether, or PGME).

In some embodiments, the method further includes applying the resultingcoating solution to a surface in a process, wherein the process is oneof a spinning, laminating, molding, or extruding process.

In some embodiments, a coating compound is manufactured by a processincluding mixing a first solvent NFM with a second solvent to form afirst solution, wherein in certain embodiments the second solvent isMEK; dissolving PAI in the first solution; precipitating a PAI compoundfrom a mixture of MEK and the first solution; and dissolving the PAIcompound in a second solution to generate a coating solution, where thesecond solution is formed with one or more of: NBP, ethylene glycol, ora solution of an a) amine, b) one or more solvents, and c) water.

In some embodiments, a film is generated from the coating composition.In some embodiments, the second solution is formed with NBP. In someembodiments, the second solution is further formed with one or moreorganic co-solvents.

In some embodiments, the coating composition is used in flexibleelectronic applications, in which electronic circuit devices are mountedon a flexible substrate, more specifically to enhance the physical andmechanical properties including but not limited to adhesion, smoothness,cracking, breaking, and flexibility of a single or multilayer filmcomprised of a conductive ink including but not limited to ITO and AGcast on a substrate including but not limited to Kapton polyimide foruse in consumer electronic applications.

In some embodiments, the coating composition is used as an additive forautomotive coating applications.

In some embodiments, the coating composition is sprayed, brushed,dipped, rolled, misted or applied via any other known method to thosewho are skilled in the art for use as a binder as in applicationsincluding but not limited to pipes, pots, pans, rubber rollers andnon-stick cookware applications alone or in combination withpolyethersulfones, polyetherimides, polyimides, or combinations thereof.

In some embodiments, the coating composition is used forcorrosion-resistance for metal or other substrates.

In some embodiments, the coating composition is used in thepre-treatment of another polymer film, such as a polyester film, apolyamide film, a polyimide film, a polyetherimide, or a polyethersulfone film, or combinations thereof.

In some embodiments, the coating composition is used as an adhesive toplastic or metallic film materials. In some embodiments, the coatingcomposition is adhered to at least one surface of a metal article orsubstrate. In some embodiments, the coating composition is used as anadditive to improve the performance of inks. In some embodiments, thecoating composition is used in an industrial spray coating such asmetallic or plastic thermal spray coating systems. In some embodiments,the coating composition is used in wire enamels and enamels in containercoating applications. In some embodiments, non-treated or heat treatedfibers coated from a film comprised of a coating composition.

FIGS. 2A-2D illustrates features of examples of implementationsaccording to a corresponding embodiment. More specifically, FIG. 2A is atable to summarize a first part of the information regarding theexamples according to the respective embodiments; FIG. 2B is a table tosummarize a second part of the information regarding the examplesaccording to the respective embodiments; FIG. 2C is a table to summarizea third part of the information regarding the examples according to therespective embodiments; and FIG. 2D is a table to summarize a third partof the information regarding the examples according to the respectiveembodiments.

In some embodiments, a process or apparatus may include one or more ofthe following examples. However, embodiments are not limited to theseexamples or the specific manner in which the examples are implemented.

Coating Composition Example I

PAI powder obtained from an NFM:MEK solution via precipitation into MEKfollowed by drying as described in Example II of U.S. provisional patentapplication 62/346,440 and U.S. patent application Ser. No. ______ wastaken and dissolved in a 100% N-butyl pyrrolidone (also referred to asTamisolvNXG commercially available from Eastman/Taminco; also known as1-Butyl-2-pyrrolidinone; herein referred to as “NBP”) solution to aconcentration of 21% solids. The viscosity (DVIII, 23° C.) was measuredand found to be 950 cP.

Coating Composition Example II

The procedure of Example I was followed except the powder was dissolvedin a 90:10 NBP:BA (BA=n-butyl acetate) solution by mass to aconcentration of 21% theoretical solids. The viscosity (DVIII, 23° C.)was measured and found to be 770 cP.

Coating Composition Example III

The procedure of Example I was followed except the powder was dissolvedin an 80:20 NBP:BA solution by mass to a concentration of 21%theoretical solids. The viscosity (DVIII, 23° C.) was measured and foundto be 645 cP.

Coating Composition Example IV

The procedure of Example I was followed except the powder was dissolvedin a 70:30 NBP:BA solution by mass to a concentration of 21% theoreticalsolids. The viscosity (DVIII, 23° C.) was measured and found to be 577cP.

Coating Composition Example V

The procedure of Example I was followed except the powder was dissolvedin a 90:10 NBP:CHN (CHN=cyclohexanone) solution by mass to aconcentration of 21% theoretical solids. The viscosity (DVIII, 23° C.)was measured and found to be 900 cP.

Coating Composition Example VI

The procedure of Example I was followed except the powder was dissolvedin an 80:20 NBP:CHN solution by mass to a concentration of 21%theoretical solids. The viscosity (DVIII, 23° C.) was measured and foundto be 832 cP.

Coating Composition Example VII

The procedure of Example I was followed except the powder was dissolvedin a 70:30 NBP:CHN solution by mass to a concentration of 21%theoretical solids. The viscosity (DVIII, 23° C.) was measured and foundto be 788 cP.

Coating Composition Example VIII

The procedure of Example I was followed except the powder was dissolvedin a 90:10 NBP:MDP (MDP=3-methoxy N,N-dimethylpropanamide; also known as“Equamide” or “Equamide M100” commercially available from Idemitsu or“KJCMPA-100” commercially available from KJ Chemicals or“3-methoxy-N,N-dimethylpropionamide” herein referred to as “MDP”)solution by mass to a concentration of 21% theoretical solids. Theviscosity (DVIII, 23° C.) was measured and found to be 893 cP.

Coating Composition Example IX

The procedure of Example I was followed except the powder was dissolvedin an 80:20 NBP:MDP solution by mass to a concentration of 21%theoretical solids. The viscosity (DVIII, 23° C.) was measured and foundto be 788 cP.

Coating Composition Example X

The procedure of Example I was followed except the powder was dissolvedin an 85:15 NBP:Oct (Oct=2-octanone) solution by mass to a concentrationof 21% theoretical solids. The viscosity (DVIII, 23° C.) was measuredand found to be 742 cP.

Coating Composition Example XI

The procedure of Example I was followed except the powder was dissolvedin a 70:30 NBP:Oct (Oct=2-octanone) solution by mass to a concentrationof 21% theoretical solids. The viscosity (DVIII, 23° C.) was measuredand found to be 606 cP.

For Coating Composition Examples I through XI the powder used was PAIpowder obtained from an NFM:MEK solution via precipitation into MEKfollowed by drying as described in Example II of U.S. provisional patentapplication 62/346,440 and U.S. patent application Ser. No. ______. Itshould be noted that other PAI powders prepared in the same fashion asdescribed in the cited embodiment may be used to make CMR-free PAIcoating solutions. As will be demonstrated, Example XI of U.S.provisional patent application 62/346,440, which is a higher acid numberPAI powder, may also be used.

Coating Composition Examples I through XI used combinations of NBP andother co-solvents such as BA, CHN, MDP, and Oct to dissolve the powderand reduce the viscosity of the resulting formulation. Various solventcombinations may be used to make coatings of the previously describedPAI powders including but not limited to N-acetyl morpholine, diethylacetamide, di-N-propyl acetamide, N-formyl morpholine,diacetylpiperazine, N,N-diisopropylacetamide, di-N-butylacetamide,di-N-propylacetamide and N-propionyl morpholine methyl actetate,n-propyl acetate, t-butyl acetate, iso-butyl acetate, ethyl acetate,isopropyl acetate, methyl lactate, ethyl lactate, n-propyl lactate,isopropyl lactate, n-butyl lactate, isobutyl lactate, t-butyl lactate,cyclohexanone, cyclopentanone, n-butyl acetate, methyl alcohol, ethylalcohol, isopropyl alcohol, anisol, ε-caprolactone, methylcyclohexane,N-n-butylpyrrolidone, N-isobutylpyrrolidone, N-t-butylpyrrolidone,N-n-pentylpyrrolidone, N-(methyl-substituted butyl) pyrrolidone,ring-methyl-substituted N-propyl pyrrolidone, ring-methyl-substitutedN-butyl pyrrolidone, N-(methoxypropyl) pyrrolidone, N-(methoxypropyl)pyrrolidone, 1,5-dimethyl-pyrrolidone and isomers thereof, dipropyleneglycol dimethyl ether, a mixture including ethyl lactate and an ethylester derived from soya bean oil or corn oil, poly(ethylene glycol)dimethyl ether, diethylene glycol diethyl ether, 1,3-dioxolane, dimethylsulphoxide, methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate,TamiSolve® NxG, propylene glycol methyl ether acetate, cholinehydroxide, propylene carbonate, diethyl carbonate, glycerine carbonate,dimethylisopropylamine and isomers thereof, dihydrolevo glucosenone,octyl pyrrolidone and isomers thereof, N-methyl-ε-caprolactam,N,N,N′,N′-tetramethylguanidine, 2-pyrrolidone, 2,2-dimethyldioxolane-4-methanol and isomers thereof, Rhodiasolv® RPDE-K,Rhodiasolv® PolarClean, Rhodiasolv® Infinity, Rhodiasolv® IRIS,diethylethanolamine and, N-ethylmorpholine, γ-hexalactone,tetrahydrofuran, furfuryl alcohol, acetophenone, cumene,cyclopentylmethyl ether, methyl-tetrahydrofuran, N-octyl pyrrolidone,dioxalane, methylethylketone, dimethylsuccinate, andN-cyclohexylpyrrolidone, or mixtures thereof the aforementionedsolvents. When using only two solvents, one example ratio of primarysolvent to co-solvent may be in a range of 99:1 to 1:99 (e.g., in arange of 90:10 to 10:90) by mass. However formulations containing 3 to 7(or more) solvents are also possible.

The viscosity is one example parameter that may be significant incoating solutions as it is directly related to the application. Forexample, the ability to effectively spray coat a PAI resin solution isdirectly related to the viscosity of the PAI coating solution. Theviscosity is a function of both the concentration of the powder as wellas the solvent mixture. For Coating Composition Examples I through XIthe concentration was kept at a 21% theoretical solids. One exampleconcentration of PAI powder coatings may be in a range of 10 to 60%solids (e.g., in a range of 20 to 50% solids). For Coating CompositionExamples I through XI the BA, CHN, MDP, and Oct co-solvent amounts werevaried to capture the effect of the co-solvents on the viscosity of thecoating solutions. The final viscosities (DVIII, 23° C.) was measuredand the relative percentage of viscosity reduction compared to a 100%NBP control was calculated. Notable NBP:co-solvent solutions used toreduce the viscosity of PAI coating solutions were the 70:30 NBP:BA,which showed a 39% relative reduction in viscosity, and the 70:30NBP:Oct which showed a 36% relative reduction in viscosity.

Coating Composition Example XII

PAI powder obtained from an NFM:MEK solution via precipitation into MEKfollowed by drying as described in Example II of U.S. provisional patentapplication 62/346,440 and U.S. patent application Ser. No. ______ wastaken and added to a solution of ethylene glycol (EG) at a concentrationof 4%. Even after 12 hours of agitation and the addition of heat (50°C.) the powder did not completely dissolve.

Coating Composition Example XIII

PAI powder as described in Example XI of U.S. provisional patentapplication 62/346,440 and U.S. patent application Ser. No. ______ wastaken and added to a solution of ethylene glycol (EG) at a concentrationof 4%. The powder easily dissolved in 2 hours.

The Coating Composition Examples XII and XIII demonstrate how utilizinga PAI powder with a different polymer structure (higher Acid Number/amicacid content) may be used to enhance solubility. The PAI powder fromExample 1 of U.S. provisional patent application 62/346,440 and U.S.patent application Ser. No. ______ had a mostly imidized structure whichwas reflected in the low Acid Number measured (<10 mg KOH/g polymer). Ascan be seen in Coating Composition Example XII of this embodiment, thepowder was only slightly (˜1%) soluble in a solution of ethylene glycol.However the PAI powder from Example XI of U.S. provisional patentapplication 62/346,440 and U.S. patent application Ser. No. ______ had adifferent structure that had mostly been converted to the polyamide amicacid as was reflected in the high Acid Number (>50 mg KOH/g polymer).Coating Composition Example XII of this embodiment shows that the highamic acid content powder was much more soluble in the ethylene glycolsolution as a 4% solids solution and was able to be dissolved in only 2hours. This solution also represents a CMR-free water-based PAI coatingsolution. The solution was coated on a Kapton™ polyimide substrate andcured at 250° C. to give a 10 μm film with excellent flexibility with nocracking when subjected to a T-bend test.

Coating Composition Example XIV

PAI powder obtained from an NFM:MEK solution via precipitation into MEKfollowed by drying as described in Example II of U.S. provisional patentapplication 62/346,440 and U.S. patent application Ser. No. ______ wastaken and slowly added to a solution containing the appropriate amountsof NMP, PGME (1-methoxy-2-propanol, or propylene glycol methyl ether),DMEA and water heated at 80° C. with agitation until dissolved (7hours).

Coating Composition Example XV

PAI powder as described in Example XI of U.S. provisional patentapplication 62/346,440 and U.S. patent application Ser. No. ______ wastaken and slowly added to a solution containing the appropriate amountsof NMP, PGME, DMEA and water heated at 80° C. with agitation untildissolved (2 hours).

Comparative Example XVI

The procedure of Example XV was followed except a commercial PAI powderwas used (AI-10 commercially available through Solvay) with slightlydifferent amounts of NMP, PGME, DMEA and water heated at 80° C. withagitation until dissolved (12 hours).

The purpose of Coating Composition Example XIV and XV and ComparativeExample XVI is to compare powder dissolution when using different typesof PAI powder to make a water-based coating formulation. Manyapplications as previously discussed require the PAI to be solubilizedin a water-miscible formulation. These particular water-based coatingswere prepared from PAI powders to concentrations of 32 to 35%. The PAIpowder concentration may be in a range of 10% to 60% solids (e.g., in arange of 20% to 50% solids). In these coating compositions, amine andwater are used to convert the polyamideimide to the polyamide amic acid.Though DMEA is used in this example due to its toxicological profile,numerous other bases or amines are possible including but not limited toTriethyl amine (TEA), Dimethylethanolamine (DMEA), trimethyl amine,diethyl 2-hydroxyethyl amine, tripropyl amine, dimethylethylamine,tributyl amine, tris(2-hydroxyethyl) amine, N,N-.dimethylaniline,.morpholine, pyridine, N-methyl-pyrrole, ethyl bis(2-hydroxyethyl)amine, and mixtures thereof. The percentage of amine in the final PAIwater-based coating may be in a range of 2% to 50% (e.g., in a range of5% to 30%) amine. Additionally the % water in the PAI water-basedformulation by mass may be in a range of 5% to 50% (e.g., in a range of5% to 35%). Though these two examples are not CMR-free due to thepresence of NMP, other CMR-free and non CMR-free coating solutions fromPAI powders are possible—e.g., by using one or more solvents such asN-acetyl morpholine, diethyl acetamide, di-N-propyl acetamide, N-formylmorpholine, diacetylpiperazine, N,N-diisopropylacetamide,di-N-butylacetamide, di-N-propylacetamide and N-propionyl morpholinemethyl actetate, n-propyl acetate, t-butyl acetate, iso-butyl acetate,ethyl acetate, isopropyl acetate, methyl lactate, ethyl lactate,n-propyl lactate, isopropyl lactate, n-butyl lactate, isobutyl lactate,t-butyl lactate, cyclohexanone, cyclopentanone, n-butyl acetate, methylalcohol, ethyl alcohol, isopropyl alcohol, anisol, n-acetyl morpholine,ε-caprolactone, methylcyclohexane, N-n-butylpyrrolidone,N-isobutylpyrrolidone, N-t-butylpyrrolidone, N-n-pentylpyrrolidone,N-(methyl-substituted butyl) pyrrolidone, ring-methyl-substitutedN-propyl pyrrolidone, ring-methyl-substituted N-butyl pyrrolidone,N-(methoxypropyl) pyrrolidone, N-(methoxypropyl) pyrrolidone,1,5-dimethyl-pyrrolidone and isomers thereof, dipropylene glycoldimethyl ether, a mixture including ethyl lactate and an ethyl esterderived from soya bean oil or corn oil, poly(ethylene glycol) dimethylether, diethylene glycol diethyl ether, 1,3-dioxolane, dimethylsulphoxide, methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate, TamiSolve® NxG, propylene glycol methyl ether acetate, choline hydroxide,propylene carbonate, diethyl carbonate, glycerine carbonate,dimethylisopropylamine and isomers thereof, dihydrolevo glucosenone,octyl pyrrolidone and isomers thereof, N-methyl-ε-caprolactam,N,N,N′,N′-tetramethylguanidine, 2-pyrrolidone, 2,2-dimethyldioxolane-4-methanol and isomers thereof, Rhodiasolv® RPDE-K,Rhodiasolv® PolarClean, Rhodiasolv® Infinity, Rhodiasolv® IRIS,γ-hexalactone, tetrahydrofuran, furfuryl alcohol, acetophenone, cumene,cyclopentylmethyl ether, methyl-tetrahydrofuran, N-octyl pyrrolidone,dioxalane, methylethylketone, dimethylsuccinate, N-methylcaprolactameand N-cyclohexylpyrrolidone, or mixtures thereof containing theaforementioned solvents.

Dissolution time of the powder as the polyamide imide is converted tothe more hydrophilic polyamide amic acid is a key parameter whenevaluating powders. As can be seen from Coating Composition Example XIV,the PAI powder used in this example took 7 hours to dissolve whereas themore hydrophilic, higher acid number powder (more amic/carboxylic acidgroups) used in Coating Composition Example XV took only 2 hours.Comparative Example XVI took 12 hours for comparison, demonstrating thatthe two example powders of this embodiment show a large improvement indissolution time relative to the commercial example. However, numerousother parameters may affect dissolution time such as the molecularweight, the particle size, presence of residual solvent or impuritiesand aspects of the primary polyamide imide structure.

The stability of PAI powder coating solutions is one example of acharacteristic that may be important in the industry as formulationsneed to be made and be able to be stable within the demands of theapplication before being converted to a coating. The stability ofCoating Composition Example XIV and XV and Comparative Example XVI wascompared by taking the solutions and comparing the initial and finalviscosity (DVIII, 23° C.) and GPC information after 7 d at 50° C. toemulate accelerated aging. The change in viscosity relative to theinitial of the coating solutions ranged from 12-52% and did not mirrorthe decrease in molecular weight. Though the viscosity may also beimportant for reasons previously described, molecular weight (Mw) may beclosely tied to performance properties of a material, and the percentageof molecular weight (Mw) changes of the samples were much less dramatic.The powder used to make Coating Composition Example XV showed an evensmaller percentage Mw loss (+1.2% within the error of the measurement;essentially no change) than the AI-10 Comparative Example XVI,demonstrating that the powder used in the formulation may be used tomake PAI coating solutions with improved Mw stability.

Coating Composition Example XVII

PAI powder obtained from an NFM:MEK solution via precipitation into MEKfollowed by drying as described in Example II of U.S. provisional patentapplication 62/346,440 and U.S. patent application Ser. No. ______ wastaken and slowly added to a solution containing the appropriate amountsof NMP, furfuryl alcohol, DMEA and water heated at 80° C. with agitationuntil dissolved (7 hours). The solution was then diluted to 4% solidsusing ethylene glycol.

Both the solution from Coating Composition Example 13 and CoatingComposition Example 17 described above were cast onto Kapton™ polyimidesubstrates using a 20 mil birdbar at a rate of 0.3 m/s to give filmswith a thickness of 10 μm. The films were cured in an oven usingseparate cure profiles, and displayed excellent adhesion and flexibilityas determined by bending the films 180° over a 1 mm rod. No cracking oradhesion loss was observed.

In this embodiment, the PAI powders can be used as described in thecoating solution examples above as a smoothing layer and adhesion tielayers for applications in the consumer electronics industry, such asink additives. Utilizing these PAI coating formulations alone or inconjunction with ITO (Indium tin oxide) or Ag inks could result insingle or multilayer materials with enhanced adhesion to and waterresistance on Kapton™ as well as additional substrates and otherimproved mechanical properties.

Coating Application Example XVIII-XXIII

PAI coating composition as described in Example II of U.S. provisionalpatent application 62/346,440 and U.S. patent application Ser. No.______ was drawn down on various substrates (glass, aluminum, steel, andKapton™) using bird bars of differing thickness (2 mil-50 mil). Thesubstrate was prepared by cleaning with organic solvents, followed bydrying for >20 minutes at 130° C. PAI powder redissolved in solventformulations was displaced in front of the leading edge of the bird bar,which was then drawn down to create a film of the desired wet thickness.The preferred concentration range is 18 to 40% solids. It has alreadybeen noted that the concentration will affect the thickness of theresulting coating. When using a doctor blade, the percentage of solidsvalue of the resin will indicate the dried coating thickness; the wet vsdry thickness of the film is relative to the percentage of solids. Thepreferred viscosity for drawdown applications is 500-5000 cP. Drawdownswere performed at a rate of 0.3 m/s. It is noted that the viscosityrange may change based on the preferred application method (for example,using a spray nozzle). The coated substrates were placed in an oven andsubjected to an appropriate cure profile.

Cure profiles for coatings described in Example XVIII-XXIII of U.S.provisional patent application 62/347,220, filed as U.S. patentapplication Ser. No. ______, are dictated by the solvent formulation inwhich the PAI powder is dissolved. Isothermal steps in the cure profileare determined by solvent formulation boiling points. The initial dryoff period of cure profiles occurs between 50 and 130° C. The curetemperature then ramps to a point 30 to 70° C. below the lowest boilingpoint of those in the solvent formulation. This step is repeated foreach solvent boiling point. After these ramping and isothermal steps,the coating is exposed to curing temperature ranging from 230 to 260° C.This final step fully evaporates remaining solvent, as well as cures thePAI coating. The isothermal steps range from 5 to 30 minutes, with ramprates ranging from 3 to 8° C. per minute.

Film quality is initially evaluated via visual inspection and mechanicaltesting, with chemical and electrical resistance following. Cureprofiles are refined to minimize time while maximizing performance.Comparison of properties with previously commercially successful sampleswas used to evaluate formulation and curing efficacy.

What is claimed is:
 1. A method for manufacturing a coating composition,the method comprising: mixing a first solvent, the first solvent beingN-formyl morpholine (NFM), with a second solvent to form a firstsolution, the first solution including polyamideimide or polyamide amicacid resin polymer (PAI); precipitating a PAI compound from a mixture ofMEK and the first solution; and dissolving the PAI compound in a secondsolution to generate a coating solution, wherein the second solutionincludes one or more of: N-butyl pyrrolidone (NBP), ethylene glycol, ora solution of an a) amine, b) one or more solvents, and c) water.
 2. Themethod of claim 1, wherein the second solvent is methyl ethyl ketone(MEK).
 3. The method of claim 1, wherein the second solution includesNBP.
 4. The method of claim 3, wherein the second solution furtherincludes one or more organic co-solvents.
 5. The method of claim 4,wherein the one or more co-solvents includes n-butyl acetate.
 6. Themethod of claim 4, wherein the one or more co-solvents includescyclohexanone.
 7. The method of claim 4, wherein the one or moreco-solvents includes 3-methoxy N,N dimethylpropanamide (MDP).
 8. Themethod of claim 4, wherein the one or more co-solvents includes2-octanone.
 9. The method of claim 1, wherein the second solution is100% ethylene glycol.
 10. The method of claim 9, wherein the firstsolution for dissolving of the PAI further includes Triethyl amine (TEA)and water to generate a tertiary amine salt of the polyamide-amic acidprior to precipitation.
 11. The method of claim 1, wherein the secondsolution comprises a) an amine, b) one or more solvents, and c) water.12. The method of claim 11, wherein the amine is a tertiary aliphaticamine, the amine being dimethylethanolamine (DMEA), and wherein the oneor more co-solvents are N-methylpyrrolidone (NMP) and1-methoxy-2-propanol (propylene glycol methyl ether, or PGME).
 13. Themethod according to claim 1, further comprising applying the resultingcoating solution to a surface for a process, the process being one of aspinning, laminating, molding, or extruding process.
 14. A coatingcompound generated by a process comprising: mixing a first solvent, thefirst solvent being N-formyl morpholine (NFM), with a second solvent, toform a first solution; dissolving polyamideimide or polyamide amic acidresin polymer (PAI) in the first solution; precipitating a PAI compoundfrom a mixture of MEK and the first solution; and dissolving the PAIcompound in a second solution to generate the coating compound, thesecond solution including one or more of: N-butyl pyrrolidone (NBP),ethylene glycol, or a solution of an a) amine, b) one or more solvents,and c) water.
 15. The coating compound of claim 14, wherein the secondsolvent is methyl ethyl ketone (MEK).
 16. The coating compound of claim14, further comprising generating a film from the coating compound. 17.The coating compound of claim 14, wherein the second solution includesNBP.
 18. The coating compound of claim 17, wherein the second solutionis further formed with one or more organic co-solvents.
 19. The coatingcompound of claim 14, wherein the process further comprises applying thecoating compound in an electronic applications as a single or multilayerfilm including a conductive ink.
 20. The coating compound of claim 14,wherein the process further comprises applying the coating compound asan additive for an automotive coating application.
 21. The coatingcompound of claim 14, wherein the process further comprises applying thecoating compound by spraying, brushing, dipping, rolling, misting, orother technique as a binder in an application including one or pipes,pots, pans, rubber rollers and non-stick cookware applications alone orin combination with polyethersulfones, polyetherimides, polyimides, orcombinations thereof.
 22. The coating compound of claim 14, wherein theprocess further comprises applying the coating compound forcorrosion-resistance for a metal substrate or other substrate.
 23. Thecoating compound of claim 14, wherein the process further comprisesapplying the coating compound in pre-treatment of another polymer film,wherein the another polymer film includes a polyester film, a polyamidefilm, a polyimide film, a polyetherimide, or a polyether sulfone film,or combinations thereof.
 25. The coating compound of claim 14, whereinthe process further comprises applying the coating compound as anadhesive to plastic or metallic film materials.
 26. The coating compoundof claim 14, wherein the process further comprises applying the coatingcompound as an additive to improve performance of inks.
 27. The coatingcompound of claim 14, wherein the process further comprises applying thecoating compound in an industrial spray coating in a metallic or plasticthermal spray coating systems.
 28. The coating compound of claim 14,wherein the process further comprises applying the coating compound inwire enamels and enamels in container coating applications.
 29. Thecoating compound of claim 14, wherein the process further comprisesapplying the coating compound is applied in non-treated or heat treatedfibers, wherein the fibers are coated from a film utilizing the coatingcompound.
 30. The coating compound of claim 14, wherein the processfurther comprises applying the coating compound to a polyimide filmsurface.